Modification of multiwall carbon nanotubes by electron irradiation: An ESR study

Multiwall carbon nanotubes were irradiated by 2.5-MeV electrons with different fluences. Nanotubes appear to be very resistant to radiation, without radiolysis effects. The radiation-induced defects, which were nearly exclusively point defects, were found to significantly modify the electronic properties of the tubes near the Fermi level, as assessed by electron spin resonance. Pristine nanotubes appeared nearly free of paramagnetic defects, the density of which increased with the fluence. Furthermore, the position of the Fermi level as monitored by the g factor was very sensitive to the presence of defects in the rolled graphene plane.